A write to the stream interface is performed by MicroBlaze V using one of the PUT or PUTD custom instructions. A write operation transfers the register contents to an output interface. The transfer is completed in a single clock cycle for blocking mode writes (PUT and CPUT custom instructions) as long as the interface is not busy. If the interface is busy, the processor stalls until it becomes available. The non-blocking custom instructions (with prefix n), always complete in a single clock cycle even if the interface is busy. If the interface is busy, the write is inhibited and the C bit is set in the mstream CSR.
The control custom instructions (with prefix c) set the AXI4-Stream
TLAST output, to 1, which is commonly used to indicate the boundary of
a packet.